1. Field of the Disclosure
The present disclosure is generally directed to methods and apparatuses for handling drill pipe and other tubular members during drilling and/or workover operations of a well, and in particular to a drill floor mounted racking arm for lifting and positioning drill pipe stands.
2. Description of the Related Art
Drilling masts are vertical structures that are commonly used to support a drill string while a well is being drilled. Drilling masts usually have a relatively compact, rectangular footprint, as opposed to a derrick structure, which typically has a steep pyramidal shape. The rectangular shape of the typical drilling mast also offers relatively good overall stiffness, which allows the mast to be lowered to a horizontal position. The compact, rectangular shape of the drilling mast structure therefore facilitates transportation of the drilling rig over surface roads, many times without the need for obtaining special shipping permits, and thereby making drilling masts very common on portable land-based (onshore) drilling rigs. FIG. 1A shows an elevation view of an illustrative portable land-based drilling rig 1 having a drilling mast 2.
During typical drilling operations, a string of drill pipe—shown as reference number 6 in FIG. 1A—which may have a drill bit or other equipment mounted on the lower end thereof, may be suspended from a traveling block 3 and top drive assembly 4 in the drilling mast 2. As may be required for certain drilling operations, the top drive 4 assembly imparts a rotational force to the drill string 6, thereby turning the drill bit and advancing the depth of the drilled wellbore. As the depth of the wellbore increases, additional lengths of drill pipe are added to the drill string 6 at the surface.
Due to the relatively compact footprint that may be associated with drilling mast structures, there may be very limited space available for storing the drill pipe and other tubular members adjacent to the drilling mast 2. Therefore, in many cases, the drill pipe is usually vertically staged in a specially designed structural assembly—often referred to as a racking board or fingerboard 5—that is attached to the drilling mast 2, as shown in FIG. 1A. The fingerboard 5 is designed to facilitate the vertical arrangement of the various sections of drill pipe that are used during the drilling operations. While the fingerboard 5 is commonly attached directly to the drilling mast 2, it may be positioned many feet—for example, 75 feet or more—above the drill floor 7, depending on the length of the various sections of staged drill pipe. FIGS. 1B and 1C show a close-up elevation view and a plan view, respectively, of the position of the fingerboard 5 relative to the drilling mast 2, the traveling block 3, the top drive assembly 4, and the drill string 6.
“Tripping” is a term of art used in drilling operations that generally refers to acts of either adding multiple joints of drill pipe to, or removing multiple joints of drill pipe from, a drilled wellbore. Oftentimes during the drilling operations, tripping operations may be performed wherein the drill string 6 is pulled from the wellbore in order to change the drill bit, or to run various other types of equipment, such as testing equipment and the like, into the wellbore on the end of the drill string 6. When tripping drill pipe out of the wellbore, a drill pipe elevator, which is typically suspended from the traveling block 3/top drive assembly 4 by pipehandler links 4a (see, FIG. 1B), is removably coupled to the upper end, or box end, of the drill string, and the elevator is raised by the traveling block 3/top drive assembly 4 until a “stand” of drill pipe (i.e., one or more sections, or joints, of drill pipe) extends above the drilling rig floor. Depending on the size of the drilling rig mast and/or the target depth of the drilling operations, a stand of drill pipe that is added to or removed from the drill string may include anywhere from one to three joints of drill pipe, where each joint has a “random” length of approximately 30-35 feet. However, in most modern land-based rigs, a stand of drill pipe often includes two (doubles) or three (triples) joints of drill pipe, with the most common drill pipe stand configuration including three joints of drill pipe, totaling approximately 90-100 feet in length. Thereafter, slips are placed between the string of drill pipe and the drilling rig floor in order to suspend the drill string 6 in and above the wellbore from a point beneath the bottom threaded joint of the stand of drill pipe that is to be removed from the drill string. In this position, the drill string 6 suspended by the slips extends above the drill floor 7, and the box end of the string 6 is positioned above the plane of the fingerboard 5, which, as noted previously, may be located 75 feet or more above the drill floor 7.
Once the drill string 6 has been suspended with its box end positioned above the fingerboard 5, the threaded connection between the stand of drill pipe and the remainder of the drill string 6 is then unthreaded, and the lower end, or pin end, of the stand is guided away from the remainder of the drill string 6 and wellbore and positioned above a support pad—sometimes referred to as a setback—on the drill floor 7. Once the pin end of the removed drill pipe stand is positioned above the setback, the traveling block 3 is lowered until the weight of the stand is supported on the setback by the pin end. Next, the box end of the drill pipe is uncoupled from the elevator and the box end of the stand is guided to the fingerboard 5 where it is staged between a set of racking fingers 8 (see FIG. 1C) in a substantially vertical orientation. In this position, the box end of the removed stand of drill pipe remains a few feet above the plane 5p of the fingerboard 5. The top drive assembly 4 is then lowered by the traveling block 3 to the box end of the drill string 6 that is suspended by the slips in the wellbore and the elevator is again coupled to the drill string 6. Thereafter, the drill string 6 is once again lifted to a position where the box end is positioned above the plane 5p of the fingerboard 5, and the process is repeated until all of the sections of pipe—e.g., in three joint stands—are supported by their respective pin ends on the setback, with their respective box ends being constrained between pairs of racking fingers 8 on the fingerboard 5. When a new drill bit or other type of tool is being run into the well, the above-described tripping process is reversed and repeated, as the pin end of each stand of drill pipe is threaded into the box end of the drill string 6 suspended by the slips at the drill floor 7, and the drill string 6 is lowered until the drill bit or other tool reaches a desired depth in the wellbore.
On many land-based (onshore) drilling rigs, the movement and guidance of the stands of drill pipe to and from the setback area of the drill floor 7, as well as to and from the traveling block 3/top drive assembly 4 to the racking fingers 8 of the fingerboard 5, has historically been performed manually by the various rig personnel, who may pull and/or push the drill pipe to its proper staging location. However, it is generally well understood that such guidance and movement of large sections of drill pipe may involve a variety of handling difficulties, particularly as drilling rigs have become larger and wellbore depths have become greater—factors which can often lead to larger diameter drill pipe, and longer and heavier drill pipe stands. For example, as the length of drill pipe stands increases, such as with doubles and triples, they can become more susceptible to swaying when supported from the uppermost box end by the traveling block 3/top drive 4, due to various operational and/or environmental conditions (e.g., wind, etc.). In such cases, manual guidance and control of the lowermost pin end of the drill pipe stand between the wellcenter and the setback can be cumbersome and difficult, due to the momentum of the swaying drill pipe stand. Furthermore, maneuvering the upper end of the drill pipe stand to or from its proper staging location in the fingerboard 5 generally requires manually uncoupling the box end of the stand from (or manually coupling the box end to) the drill pipe elevator, and manually moving the upper end of the stand of drill pipe from its location at or near the centerline 9 of the well (i.e., the wellcenter) over to and into the racking fingers 8 of the fingerboard 5, and vice versa. In order to enable rig personnel to perform these coupling, uncoupling, and movement activities, the fingerboard 5 usually includes access platforms 10 adjacent to and surrounding the racking fingers 8. The fingerboard 5 may also sometimes include an additional access platform 11, sometimes referred to as a diving board 11, in order to facilitate easier access to the elevator, the traveling block 3, the top drive assembly 4, and/or the drill string 6. In most cases, the diving board 11 is configured so as to run down the center of the fingerboard 5—i.e., between rows of racking fingers 8—and extend away from the fingerboard 5 and toward the centerline 9 of the well, as shown in FIG. 1C. Additionally, the diving board 11 sometimes includes a hinged extension section 11a, which can be folded out for closer access to the centerline 9 of the well, or folded back to provide more clearance between the traveling block 3 or top drive assembly 4 and the diving board 11 during some rig operations.
In order to increase overall efficiency and consistency in handling drill pipe during the time-consuming—and thus costly—tripping operations, various prior art mechanical systems have been developed to lift and/or guide the stands of drill pipe between the wellcenter and the setback and fingerboard 5, thus freeing up at least some rig personnel to perform or monitor other rig operations. For example, FIGS. 2A-2C are various isometric views of one prior art mechanical pipe handling system 20 that has been used in some drilling applications to handle and move drill pipe stands during tripping operations.
FIG. 2A is an isometric view of a pipe handling system 20, which includes a vertical support 21 that supports an upper arm assembly 22a and a lower arm assembly 22b. The upper arm assembly 22a includes a lift jaw assembly 26a that is used to grip an upper end of a stand 50 of drill pipe, i.e., near the box end 50b, and to fixedly hold and guide the drill pipe stand 50 as it is moved around during drilling operations. Furthermore, the upper arm assembly 22a can be raised and lowered along the vertical height of the vertical column 21 by a hoist carriage 33, as will be further described below. The lower (tailing) arm assembly 22b includes a guide claw assembly 26b that is used to capture (but not grip) and guide the lower end of the drill pipe stand 50, i.e., near the pin end 50p, during movement of the stand 50, and as the stand 50 is being raised or lowered by the upper arm assembly 22a and lift jaw assembly 26a. 
The pipe handling system 20 also includes a floor track 23b that is fixed to the drill floor of a drilling rig, i.e., to the setback area, and the lower end of the vertical column 21 includes a lower drive assembly 24b that is operatively coupled to the floor track 23b. Additionally, an upper track 23a is coupled to and positioned in front of a fingerboard 25, or between a pair of fingerboards 25, that extend laterally away from the upper track 23a, and the upper end of the vertical column 21 includes an upper drive assembly 24a that is operatively coupled to the upper track 23a. The fingerboards 25 are typically fixed to the rig mast or derrick, or to a structure positioned adjacent to the mast or derrick, depending on the type of drilling rig on which the pipe handling system 20 is used. During pipe handling operations, the upper and lower drive assemblies 24a, 24b are operated in tandem so as to move the vertical column 21 back and forth along the upper track 23a and the floor track 23b, that is, between or in front of the fingerboards 25 and across the rig setback, as will be described further in conjunction with FIGS. 2B and 2C below. Furthermore, the drive assemblies 24a, 24b and the track 23a, 23b are configured so that a vertical axis 21x of the vertical column 21 is maintained in a vertical orientation, that is, substantially perpendicular to the drill floor, as the vertical column 21 is moved along the tracks 23a, 23b. 
The upper and lower arm assemblies 22a, 22b are coupled to the vertical column 21 such that each is in the same orientation relative to the vertical axis 21x. In this way, the lift jaw assembly 26a of the upper arm assembly 22a is always positioned directly vertically above the guide claw assembly 26b of the lower arm assembly 22b, thus enabling the pipe handling system 20 lift and move the drill pipe stand 50 while the stand 50 is maintained in a substantially vertical orientation. A column rotation assembly 39 is positioned at the lower end of the vertical column 21 and above the lower drive assembly 24b, and is configured to rotate the vertical column 21 about the vertical axis 21x relative to each of the tracks 23a, 23b. Thus, the drive assemblies 24a, 24b can be used to move the vertical column 21 along the tracks 23a, 23b and the column rotation assembly 39 can be used to rotate the column 21 so that the upper and lower arm assemblies 22a, 22b are properly positioned and orientated for grabbing a drill pipe stand, such as the stand 50, from any position within the fingerboard 25. Once positioned and oriented in this manner, the lift jaw assembly 26a is used to grab and fixedly hold the drill pipe stand 50, the hoist carriage 33 is used to raise the upper arm 22a so that the pin end 50p of the stand 50 is lifted off of the setback, and the lift jaw assembly 26a and the guide claw assembly 26b are used to guide the stand 50 out of the fingerboard 25 and over to the wellcenter as the vertical column 21 is moved along the tracks 23a, 23b and rotated into position by the column rotation assembly 39.
After the drill pipe stand 50 is positioned above the wellcenter, the upper arm assembly 22a is then lowered by the hoist carriage 33 so that the pin end 50p of the stand 50 can be engaged with and threadably coupled to a box end of a drill string that is suspended by slips in the wellbore (not shown in FIGS. 2A-2C). As noted previously, the guide claw assembly 26b captures, but does not grip, the drill pipe stand 50, and therefore does not restrict the vertical (up and down) movement of the stand 50 during raising and lowering operations. Accordingly, during this stand lowering operation, the stand 50 simply slides through the guide claw assembly 26b. Once the stand 50 has been threadably coupled to the drill string, a drill pipe elevator (not shown) that is supported from a traveling block/top drive assembly (not shown) is coupled to the box end 50b of the drill pipe stand 50, the lift jaw assembly 26a releases its grip on the stand 50, the upper and lower arm assemblies 22a, 22b are retracted so that the lift jaw assembly 26a and the guide claw assembly 26b are moved away from the stand 50 and the slips are removed from the drill string. Thereafter, the drill string with the newly attached drill pipe stand 50 is lowered into the wellbore by the traveling block/top drive assembly, or in some operations the drill sting can be lowered using the pipe handling system 20, after which the slips are reset and the process repeated for the next drill pipe stand 50.
FIGS. 2B and 2C are close-up isometric views of the lower arm assembly 22b and the upper arm assembly 22a, respectively, and show some additional detailed aspects of the prior art pipe handling system 20. As shown in FIG. 2B, the pipe handling system 20 includes a horizontal travel motor 29 that is coupled to a gearbox 30, which is used to drive a vertical driveshaft (not shown) that extends upward inside of the vertical column 21. The vertical driveshaft is coupled to and used to drive the upper drive assembly 24a, which includes an upper drive shaft (not shown) that is coupled to the upper end of the vertical drive shaft. The vertical drive shaft drives an upper drive pinion gear (not shown), which in turn engages an upper track gear rack 32a (see, FIG. 2C) so as to move the upper end of the vertical column 21 along the upper track 23a. The gearbox 30 is also coupled to the lower drive assembly 24b, which includes a lower drive shaft (not shown), which is used to drive a lower drive pinion gear 31b that engages a floor track gear rack 32b and moves the lower end of the vertical column 21 along the floor track 23b. Therefore, since the upper and lower drive assemblies 24a and 24b are driven simultaneously by the horizontal travel motor 29, they are appropriately geared so as to allow the vertical column 21 to remain vertical during it horizontal movement along the tracks 23a and 23b. 
The column rotation assembly 39 includes a rotation drive motor 28 that is coupled to rotation drive pinion gear (not shown), which in turn engages a rotation drive ring gear (not shown) so as to rotate the vertical column 21 about the column axis 21x, as is required to orient the upper and lower arm assemblies 22a, 22b during pipe handling operations. A lower arm extension cylinder 27b is pivotably coupled to the vertical column 21 and the lower arm assembly 23b. The extension cylinder is used to extend the lower arm assembly 23b away from the vertical column 21 so that the guide claw assembly 26b can engage and guide the lower end of the drill pipe stand 50, and to retract the lower arm assembly 23b back from the drill pipe stand 50 once the stand has been released by the lift jaw assembly 26a. 
The pipe handling system 20 also includes a pair of wire rope spooling drums 35, each of which is driven by respective hoist motors 36 (one only shown in FIG. 2B). The wire rope 34 that is spooled around each of the drums 35 is sheaved about respective crown sheaves 37 that are coupled to opposing sides of the upper end of the vertical column 21, and about respective wire rope sheaves 38 that are coupled to opposing sides of the hoist carriage 33. See, FIG. 2C. The pair of hoist motors 36 are used to raise and lower the hoist carriage 33 so as to raise and lower the upper arm assembly 22a, and to raise and lower the drill pipe stand 50 when it is gripped and fixedly held by the lift jaw assembly 26a. 
A plurality of upper column rotation guide rollers 40 are coupled to the upper end of the vertical column 21 so as to facilitate the rotation of the vertical column 21 about the column axis 21x by the column rotation assembly 39. An upper arm extension cylinder 27a is pivotably coupled to the vertical column 21 and the upper arm assembly 23a, and is used to extend the upper arm assembly 23a away from the vertical column 21 so that the lift jaw assembly 26a can grip and guide the upper end of the drill pipe stand 50 during pipe handling operations, and to retract the upper arm assembly 23a after the lift jaw assembly 26a has released the stand 50.
As shown in FIGS. 2A-2C, the upper and lower arm assemblies 22a, 22b are positioned on the same side of the vertical column 21. Therefore, both arm assemblies 22a, 22b will always be oriented in the same direction relative to the column axis 21x, irrespective of how the column rotation assembly 39 might rotate the column 21. Furthermore, in order to keep the drill pipe stand 50 in a substantially vertical orientation during pipe handling operations, the lift jaw assembly 26a must be positioned directly above the guide claw assembly 26b. Therefore, the upper and lower arm assemblies 22a, 22b must generally be operated in tandem, i.e., together, in order to lift and move drill pipe stands around a drilling rig. As such, it should be appreciated that the upper arm assembly 22a cannot be operated independently of the lower arm assembly 22b so as to grab and lift an upper end of one drill pipe stand while the lower arm assembly 22b is operated to guide a lower end of a different drill pipe stand.
Additionally, as noted above, the floor track 23b of the pipe handling system 20 is typically fixed to the drill floor in the setback area and the upper track 23a is coupled to the fingerboards 25, which are in turn typically fixed to the rig mast/derrick, or to a structure positioned adjacent to the mast/derrick. As such, when it is not being used for pipe handling operations, the pipe handling system 20 generally cannot be moved off of the drill floor and/or out of the way—other than the vertical column 21 being moved back along the tracks 23a, 23b and away from the wellcenter—so that drill floor space can be freed up for performing other rig operations. This can be problematic in some applications, particularly for operations performed with portable land-based (onshore) rigs, where drill floor space is at a premium. Therefore, pipe handling systems such as the system 20 are typically used for offshore applications, where the system 20 is an integral part of the overall rig design, and the layout of the drill floor space can be specifically designed around the configuration of the system 20.
The present disclosure directed to methods, systems, and apparatuses that may be used to address of one or more of the design and/or operational issues outlined above.